Worldwide aviation emissions pump slightly more pollution into the atmosphere than the entire United Kingdom economy, and aviation emissions continue relentlessly to increase year after year. Air transport is simply far too cheap for the damage it causes and the resources it consumes. You cannot cause more damage to the Earth’s atmosphere with £30 worth of resources, than by buying a £30 Ryanair ticket to Barcelona. If you spend that £30 on fuel for your diesel car, or on coal and burn it in your garden, you will not come close to the damage caused by your share of emissions on that Ryanair flight.

Murray describes a major reason the flights are so cheap: jet fuel isn't taxed, on the premise that if it was, the airline would just buy the fuel somewhere else. It is apparently too complicated to have different prices for fuel in different countries. The rail companies, however, have to pay the full tax on fuel.

There are other reasons, of course. There is incredible competition between the RyanAirs and the EasyJets. If it was just fuel, then we would fly this cheaply in North America. The home of economic freedom and fair competition, the USA, prohibits foreign airlines from operating domestically, whereas in Europe, everyone can fly everywhere and big airlines have to compete with little startups. As Rick Noack writes in the Washington Post,

Germany’s airline top dog Lufthansa, for example, might be well advised to not ignore the offerings of Iceland’s Wow Air on German territory. The fact that no country is safe from international competition is driving prices for customers downward.

Noack also suggests that Europe’s much higher density of cities and smaller — previously underused — airports were a natural advantage for the low-budget carriers. They can offer tickets to smaller airports at much lower cost because landing fees there are usually less expensive.

But Europe's higher density and closer cities also could make rail competitive, which it is not. Murray admits that "the farce and greed of rail privatisation is also a large part of it." Murray then concludes:

The Earth cannot afford to indulge the pollution caused by massive air tourism. The unpopularity of saying this means that few people in politics ever do, but it is nonetheless true. In view of climate change, for the public to expect Ryanair fare levels is obscene. Mass air travel for leisure needs to be stopped. Maritime, rail and other more eco-friendly means of international communication need to be encouraged. As mankind has not even the political will to tackle these most straightforward of measures on climate change, I really do begin to despair for the future.

Murray says, "There is no human right to go by air and have a sun-soaked holiday on the Med dirt cheap." Of course not; he could move to the USA and pay five times as much to travel the same distance. But he is not alone in thinking that mass air travel needs to be stopped. The key is to develop some decent alternatives.